<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>烟花动画特效</title>

<style>
:root {
  font-family: "Aleo", sans-serif;
  color:red
}

html,
body {
  width: 100%;
  height: 100%;
  padding: 0;
  margin: 0;
  background: rgb(42, 19, 239);

}

canvas {
  width: 100%;
  height: 100%;
}

.middle {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  text-align: center;
  user-select: none;
}


</style>
</head>
<body>
<div class="middle">
 <h1 class="label">2022 新的一年 </h1>
                <h2 class="label">元旦快乐  </h2>

</div>

<canvas id="canvas"></canvas><script>
function initVars(){

 pi=Math.PI;
 ctx=canvas.getContext("2d");
 canvas.width=canvas.clientWidth;
 canvas.height=canvas.clientHeight;
 cx=canvas.width/2;
 cy=canvas.height/2;
 playerZ=-25;
 playerX=playerY=playerVX=playerVY=playerVZ=pitch=yaw=pitchV=yawV=0;
 scale=600;
 seedTimer=0;seedInterval=5,seedLife=100;gravity=.02;
 seeds=new Array();
 sparkPics=new Array();
 s="https://cantelope.org/NYE/";
 for(i=1;i<=10;++i){
  sparkPic=new Image();
  sparkPic.src=s+"spark"+i+".png";
  sparkPics.push(sparkPic);
 }
 sparks=new Array();
 pow1=new Audio(s+"pow1.ogg");
 pow2=new Audio(s+"pow2.ogg");
 pow3=new Audio(s+"pow3.ogg");
 pow4=new Audio(s+"pow4.ogg");
 frames = 0;
}

function rasterizePoint(x,y,z){

 var p,d;
 x-=playerX;
 y-=playerY;
 z-=playerZ;
 p=Math.atan2(x,z);
 d=Math.sqrt(x*x+z*z);
 x=Math.sin(p-yaw)*d;
 z=Math.cos(p-yaw)*d;
 p=Math.atan2(y,z);
 d=Math.sqrt(y*y+z*z);
 y=Math.sin(p-pitch)*d;
 z=Math.cos(p-pitch)*d;
 var rx1=-1000,ry1=1,rx2=1000,ry2=1,rx3=0,ry3=0,rx4=x,ry4=z,uc=(ry4-ry3)*(rx2-rx1)-(rx4-rx3)*(ry2-ry1);
 if(!uc) return {x:0,y:0,d:-1};
 var ua=((rx4-rx3)*(ry1-ry3)-(ry4-ry3)*(rx1-rx3))/uc;
 var ub=((rx2-rx1)*(ry1-ry3)-(ry2-ry1)*(rx1-rx3))/uc;
 if(!z)z=.000000001;
 if(ua>0&&ua<1&&ub>0&&ub<1){
  return {
   x:cx+(rx1+ua*(rx2-rx1))*scale,
   y:cy+y/z*scale,
   d:Math.sqrt(x*x+y*y+z*z)
  };
 }else{
  return {
   x:cx+(rx1+ua*(rx2-rx1))*scale,
   y:cy+y/z*scale,
   d:-1
  };
 }
}

function spawnSeed(){

 seed=new Object();
 seed.x=-50+Math.random()*100;
 seed.y=25;
 seed.z=-50+Math.random()*100;
 seed.vx=.1-Math.random()*.2;
 seed.vy=-1.5;//*(1+Math.random()/2);
 seed.vz=.1-Math.random()*.2;
 seed.born=frames;
 seeds.push(seed);
}

function splode(x,y,z){

 t=5+parseInt(Math.random()*150);
 sparkV=1+Math.random()*2.5;
 type=parseInt(Math.random()*3);
 switch(type){
  case 0:
   pic1=parseInt(Math.random()*10);
   break;
  case 1:
   pic1=parseInt(Math.random()*10);
   do{ pic2=parseInt(Math.random()*10); }while(pic2==pic1);
   break;
  case 2:
   pic1=parseInt(Math.random()*10);
   do{ pic2=parseInt(Math.random()*10); }while(pic2==pic1);
   do{ pic3=parseInt(Math.random()*10); }while(pic3==pic1 || pic3==pic2);
   break;
 }
 for(m=1;m<t;++m){
  spark=new Object();
  spark.x=x; spark.y=y; spark.z=z;
  p1=pi*2*Math.random();
  p2=pi*Math.random();
  v=sparkV*(1+Math.random()/6)
  spark.vx=Math.sin(p1)*Math.sin(p2)*v;
  spark.vz=Math.cos(p1)*Math.sin(p2)*v;
  spark.vy=Math.cos(p2)*v;
  switch(type){
   case 0: spark.img=sparkPics[pic1]; break;
   case 1:
    spark.img=sparkPics[parseInt(Math.random()*2)?pic1:pic2];
    break;
   case 2:
    switch(parseInt(Math.random()*3)){
     case 0: spark.img=sparkPics[pic1]; break;
     case 1: spark.img=sparkPics[pic2]; break;
     case 2: spark.img=sparkPics[pic3]; break;
    }
    break;
  }
  spark.radius=25+Math.random()*50;
  spark.alpha=1;
  spark.trail=new Array();
  sparks.push(spark);
 }
 switch(parseInt(Math.random()*4)){
  case 0: pow=new Audio(s+"pow1.ogg"); break;
  case 1: pow=new Audio(s+"pow2.ogg"); break;
  case 2: pow=new Audio(s+"pow3.ogg"); break;
  case 3: pow=new Audio(s+"pow4.ogg"); break;
 }
 d=Math.sqrt((x-playerX)*(x-playerX)+(y-playerY)*(y-playerY)+(z-playerZ)*(z-playerZ));
 pow.volume=1.5/(1+d/10);
 pow.play();
}

function doLogic(){

 if(seedTimer<frames){
  seedTimer=frames+seedInterval*Math.random()*10;
  spawnSeed();
 }
 for(i=0;i<seeds.length;++i){
  seeds[i].vy+=gravity;
  seeds[i].x+=seeds[i].vx;
  seeds[i].y+=seeds[i].vy;
  seeds[i].z+=seeds[i].vz;
  if(frames-seeds[i].born>seedLife){
   splode(seeds[i].x,seeds[i].y,seeds[i].z);
   seeds.splice(i,1);
  }
 }
 for(i=0;i<sparks.length;++i){
  if(sparks[i].alpha>0 && sparks[i].radius>5){
   sparks[i].alpha-=.01;
   sparks[i].radius/=1.02;
   sparks[i].vy+=gravity;
   point=new Object();
   point.x=sparks[i].x;
   point.y=sparks[i].y;
   point.z=sparks[i].z;
   if(sparks[i].trail.length){
    x=sparks[i].trail[sparks[i].trail.length-1].x;
    y=sparks[i].trail[sparks[i].trail.length-1].y;
    z=sparks[i].trail[sparks[i].trail.length-1].z;
    d=((point.x-x)*(point.x-x)+(point.y-y)*(point.y-y)+(point.z-z)*(point.z-z));
    if(d>9){
     sparks[i].trail.push(point);
    }
   }else{
    sparks[i].trail.push(point);
   }
   if(sparks[i].trail.length>5)sparks[i].trail.splice(0,1);
   sparks[i].x+=sparks[i].vx;
   sparks[i].y+=sparks[i].vy;
   sparks[i].z+=sparks[i].vz;
   sparks[i].vx/=1.075;
   sparks[i].vy/=1.075;
   sparks[i].vz/=1.075;
  }else{
   sparks.splice(i,1);
  }
 }
 p=Math.atan2(playerX,playerZ);
 d=Math.sqrt(playerX*playerX+playerZ*playerZ);
 d+=Math.sin(frames/80)/1.25;
 t=Math.sin(frames/200)/40;
 playerX=Math.sin(p+t)*d;
 playerZ=Math.cos(p+t)*d;
 yaw=pi+p+t;
}

function rgb(col){

 var r = parseInt((.5+Math.sin(col)*.5)*16);
 var g = parseInt((.5+Math.cos(col)*.5)*16);
 var b = parseInt((.5-Math.sin(col)*.5)*16);
 return "#"+r.toString(16)+g.toString(16)+b.toString(16);
}

function draw(){

 ctx.clearRect(0,0,cx*2,cy*2);

 ctx.fillStyle="#ff8";
 for(i=-100;i<100;i+=3){
  for(j=-100;j<100;j+=4){
   x=i;z=j;y=25;
   point=rasterizePoint(x,y,z);
   if(point.d!=-1){
    size=250/(1+point.d);
    d = Math.sqrt(x * x + z * z);
    a = 0.75 - Math.pow(d / 100, 6) * 0.75;
    if(a>0){
     ctx.globalAlpha = a;
     ctx.fillRect(point.x-size/2,point.y-size/2,size,size);
    }
   }
  }
 }
 ctx.globalAlpha=1;
 for(i=0;i<seeds.length;++i){
  point=rasterizePoint(seeds[i].x,seeds[i].y,seeds[i].z);
  if(point.d!=-1){
   size=200/(1+point.d);
   ctx.fillRect(point.x-size/2,point.y-size/2,size,size);
  }
 }
 point1=new Object();
 for(i=0;i<sparks.length;++i){
  point=rasterizePoint(sparks[i].x,sparks[i].y,sparks[i].z);
  if(point.d!=-1){
   size=sparks[i].radius*200/(1+point.d);
   if(sparks[i].alpha<0)sparks[i].alpha=0;
   if(sparks[i].trail.length){
    point1.x=point.x;
    point1.y=point.y;
    switch(sparks[i].img){
     case sparkPics[0]:ctx.strokeStyle="#f84";break;
     case sparkPics[1]:ctx.strokeStyle="#84f";break;
     case sparkPics[2]:ctx.strokeStyle="#8ff";break;
     case sparkPics[3]:ctx.strokeStyle="#fff";break;
     case sparkPics[4]:ctx.strokeStyle="#4f8";break;
     case sparkPics[5]:ctx.strokeStyle="#f44";break;
     case sparkPics[6]:ctx.strokeStyle="#f84";break;
     case sparkPics[7]:ctx.strokeStyle="#84f";break;
     case sparkPics[8]:ctx.strokeStyle="#fff";break;
     case sparkPics[9]:ctx.strokeStyle="#44f";break;
    }
    for(j=sparks[i].trail.length-1;j>=0;--j){
     point2=rasterizePoint(sparks[i].trail[j].x,sparks[i].trail[j].y,sparks[i].trail[j].z);
     if(point2.d!=-1){
      ctx.globalAlpha=j/sparks[i].trail.length*sparks[i].alpha/2;
      ctx.beginPath();
      ctx.moveTo(point1.x,point1.y);
      ctx.lineWidth=1+sparks[i].radius*10/(sparks[i].trail.length-j)/(1+point2.d);
      ctx.lineTo(point2.x,point2.y);
      ctx.stroke();
      point1.x=point2.x;
      point1.y=point2.y;
     }
    }
   }
   ctx.globalAlpha=sparks[i].alpha;
   ctx.drawImage(sparks[i].img,point.x-size/2,point.y-size/2,size,size);
  }
 }
}

function frame(){

 if(frames>100000){
  seedTimer=0;
  frames=0;
 }
 frames++;
 draw();
 doLogic();
 requestAnimationFrame(frame);
}

window.addEventListener("resize",()=>{
 canvas.width=canvas.clientWidth;
 canvas.height=canvas.clientHeight;
 cx=canvas.width/2;
 cy=canvas.height/2;
});

initVars();
frame();
</script>


</body>
</html>